Morin Béatrice. 2000. Nature de la résistance variétale de la canne à sucre au ravageur Chilo sacchariphagus Bojer (Lepidoptera : Pyralidae) : étude de la résistance de la variété R570 par rapport à la variété R579, variétés cultivées à la Réunion. Toulouse : ESAP, 134 p. Mémoire d'ingénieur : Ecole supérieure d'agriculture de Purpan
Titre anglais : Nature of the varietal resistance of sugarcane to the destructive insecto Chilo sacchariphagus Bojer (Lepidoptera : Pyralidae) : Survey on the resistant variety R570 compared to the variety R579
Résumé : The subject of this survey is : the varietal resistance of sugarcane to the destructive insect called Chilo sacchariphagus. This study has been specifically applied to the varieties R570 and R579, prevalent on Reunion island. As a matter of fact, the whole group of people working in this field consider the lepidopteran Chilo sacchariphagus as the most dangerous among the noxious insects of the sugarcane. The roots of this concern are numerous: this insect causes very important damages, the infestations have been increasing for some years and up to now, efficient means of fighting it have not been found yet. Integrated pest management appears as a new hope to supress these problems. The consequently varietal resistance, mainstay of this fight, thus arouses a great interest. The resistance of the variety R570 and the susceptibility of the variety R579 had been proved by former experiments. So that it appeared of prime importance to understand with accuracy the mechanisms which are at the origins of this resistance, in order to make the most of it. The principal aim of this survey was to identify the nature of this resistance. Consequently it was focused on the physical point of view of this phenomenom, a component of this resistance, which appeared as the most relevant considering the ravaging insect ethology. After searching for a methodology and tools adapted to the resistance estimation, we came to the conclusion of choosing a penetrometric analysis. This analysis was done together with a histological study of sound sugarcane tissues, in order to authenticate joinly the results. On the one hand, it was clearly proved there is a strong correlation between the spread out, the amount of the lignan in the studied tissues and the estimated physical resistance. The tool and the method which have been used during these penetrometric tests, proved to be perfectly fit to the searched measures. What essentially comes out is that the physical aspect of the resistance to penetration is then explained by evident biological elements. On the other hand, in term of global resistance, the varietal difference just appears in the median part of the internode and at the level of the bud. According to this survey, the mechanism of this physical resistance is linked to a different decreasing gradient of the concentration of the vascular bundles held in the pith of the middle part of the internode. In this area, the size and the distribution of the vascular bundles and of their sclerenchyma sheath consequently determine the resistance of the cane variety to the spread of the destructive insect. Moreover, some results related to chemical analysis on the parietal components confirm the physical aspect of the resistance. Concurrently to this survey we have tested the BING, a rather innovative apparatus for its measurement principle. However the first results didn't allow us to show a varietal resistance. On the whole, the results of this survey have brought to light this physical mechanism of varietal resistance. Moreover we can say the resistance phenomenom doesn't bring up a considerable increase of the fibres content at the pith level. Therefore, this last result proves extremely interesting in order to plan in the future the industrial valorization of this resistant variety.
Classification Agris : H10 - Ravageurs des plantes
Auteurs et affiliations
- Morin Béatrice, ESAP (FRA)
Autres liens de la publication
Source : Cirad - Agritrop (https://agritrop.cirad.fr/476947/)
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